Falls affect millions of people each year and result in significant injuries, particularly in the elderly. In fact, it has been estimated that falls are one of the top three causes of death in elderly people.
A fall is defined as a sudden, uncontrolled and unintentional downward displacement of the body to the ground. There are currently some fall detection systems available that detect these falls and allow the user to obtain assistance manually or automatically if a fall occurs. Exemplary fall detection systems can comprise personal help buttons (PHBs) or worn and/or environment-based automatic detection systems.
Automatic fall detection systems comprise one or a set of sensors that continuously measure the movement of the user, and a processor that compares the measured or processed signals with predetermined thresholds in order to detect a fall. In particular, automatic fall detection systems store a set of predetermined threshold values and/or classification patterns (which are hereinafter referred to as parameter sets). When the system is activated, movement data obtained from the sensors (such as, for example, an accelerometer) will be continuously transformed and processed, and then compared with those parameter sets to determine if a fall event occurs.
Many fall detection systems also calculate a change in the orientation of the fall detection system (and hence the user) and detect an impact with the ground during a fall event.
However, these systems have limitations, since impacts and fall patterns are closely related to the user's weight, and an impact for an old man who weighs 75 kg is quite different from the impact for an old lady who only weighs 45 kg. Therefore, fall detection systems should be adaptive to the size and/or weight of the human body.
Fall detection systems are often designed to be simple for an elderly user to operate, which is why a PHB is only designed with one big button to ease operation. However, it is difficult to use this single button to allow the system to be customized to particular users (for example inputting some personalized body parameters into the fall detection system). Alternative systems that include several buttons and flashing lights or displays may prove to be too complex for an elderly person to operate.